I have installed 12.04 on a dell vostro 2420 (previously 11.10) and wifi is gone now but wired network remains. I've reviewed the other questions and tried some stuff but no luck yet. The following is the process so far so hopefully someone can help:

After installing 12.04 using the additional drivers utility did not bring up any proprietary drivers and using synaptic on installation then reinstallation of bcmwl-kernel-source and b43-fwcutter does not help bring up any drivers either (tried rebooting after as well)

I have made sure in the bios that the wlan is turned on, and it appears the laptop does not have a wireless hardware switch, only the keyboard function shortcut which turns bluetooth on and off on the taskbar but there is no lightup of the wireless function on the laptop itself.

Dell does not appear to have any drivers for ubuntu and google does not appear to be much help :(

Welcome to Ask Ubuntu! We need to double check your wireless hardware information to help you, can you look at this question and then edit your question adding the information.
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fossfreedom♦Oct 18 '12 at 22:48

Please try 'sudo lspci' or 'sudo lshw' and verify the wifi card make and model. That would go a long way to help us help you. (I'm on my phone and don't have a 'back tic'. Would someone be so kind as to fix the code portion for me?)
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ArgusvisionOct 19 '12 at 0:46

The package also removes the conflicting packages from the old proprietary drivers that don't work, which I believe was what caused me problems when I tried to use the deb package in the question linked above.